- "Dog Monday waits and watches there still, with just as much hope and confidence as ever. Sometimes he hangs around the station house and talks to people and the rest of his time he sits at his little kennel door and watches the track unwinkingly. We never try to coax him home now: we know it is of no use. When Jem comes back, Monday will come home with him; and if Jem—never comes back—Monday will wait there for him as long as his dear dog heart goes on beating."
- —Rilla writes in her diary about Dog Monday[src]
The Blythe family was never very good at keeping dogs around. A few died, some wandered off, and one simply wasn't happy. Eventually Dog Monday came and he stayed.
Dog Monday's loyalty was shown when Jem went off to fight in the First World War. After the Blythe family saw Jem off at the train station, he refused to come home. That's when his long and faithful vigil started.
- "His dear master had gone-he, Monday, had been deliberately and of malice aforethought prevented from going with him by a demon disguised in the grab of a Methodist minister. Wherefore, he, Monday, would wait there until the smoking, snorting monster, which carried his hero off, carried him back."
- —Dog Monday, after Jem left.[src]
A dog house was built to keep Dog Monday warm and dry, and the butcher gave him meat scraps. Dog Monday never left the station, but met every single train, because he hoped one of them would bring his master back home.
Even though Dog Monday was Jem's dog, he was still very close to Walter. In fact, he was so close that he knew when Walter was killed. That night, Dog Monday howled the entire night. No one knew what was wrong, and after several days, it was suspected that there wasn't a particular reason for Dog Monday's howling.
After the Blythes received a telegram telling them that Walter had been killed at the Battle of Courcelette, they realized that Dog Monday's howling was actually mourning.
At the end of the war, Dog Monday was rewarded greatly for his wait when his owner finally stepped off the train.
- "Monday was never successful in affairs of honour. But he possessed one talisman. He knew that not all dogs could be handsome or eloquent or victorious, but that every dog could love. Inside his homely hide beat the most affectionate, loyal, faithful heart of any dog since dogs were; and something looked out of his brown eyes that was nearer akin to a soul than any theologian would allow."
- —Rilla of Ingleside[src]
- "Monday was not a collie or a setter or a hound or a Newfoundland. He was just, as Jem said, 'plain dog'—very plain dog, uncharitable people added. Certainly, Monday's looks were not his strong point. Black spots were scattered at random over his yellow carcass, one of them, apparently, blotting out an eye. His ears were in tatters, for Monday was never successful in affairs of honour."
- —Rilla of Ingleside[src]
Dog Monday was named by Walter as a result of his reading Robinson Crusoe, because Dog Monday arrived at Ingleside on a Monday.